Telegraph repeater circuits



Nov. 26, 1929. J. HERMAN l 1,736,786

` TELEGRAPH REPEATER CIRCUITS Filed Jan. 2o, 1928 INVENTOR JTe/w/aan/ATTORN EY Patented Nov. 26, 1929 UNITED STATES PATENT ortica JOSEPHHERMAN, OF EVESTFIELD, NEW JERSEY, ASSIGNOR T0 AMERICAN TELEEHONE ANDUGMPANY, A CORIGRATION QF NEW" YORK TELEGRAPH REPEATER CIRCUITSApplication lccl January 20, 1528.

This invention relates to an improved arrangement of through typetelegraph repeaters.

The repeater device o'li the invention consits essentially of a one wayrepeater which is automatically switched in the direction oftransmission by means of an auxiliary or break relay. The operation ofthis relay depends upon the reduction in line current when an opposingbattery is connected at the distant end of the line for purposes oi'breaking the operator at the other terminal station. Telegraph systemsin which the breaking feature at the terminal stations is controlled bythe application ot opposing battery at the distant station areillustrated and described in the Patents #1,548,088, August 4, 1925 and#1,519,202, December 16, 1924 in the name of J. Herman and reference ishad thereto. lVhile the telegraph repeater of this invention isparticularly suitable for use in a system utilizing terminal stations ofthe type described in said abovementioned patents it is understood thatits use is not so limited but that it may be utilized in other types ofsystems. It is understood that the type of repeater embraced in thislinvention is suitable for both open wire lines and full metalliccircuits and for both small and large gauge cable circuits.

The invention may be more fully under-r stood from the accompanyingdrawing in the tive batteries 2 and 3 respectively on itsl spacing andmarking cont-acts designated as S and M respectively. The pole changerrelay 1 has three windings 4, 5 and 6. 4 and 5 are balanced windings, 4being connected into a biasing circuit 8, and 5 being connected into theloop circuit 7.y The third winding 6 consists of a large number of turnsSerial No. 248,134.

connected across the armature and a contact of the receiving relay 10.It serves as a holding winding for the pole changer during the operationof the receiving relay 10. This arrangement has been disclosed in detail1n a Patent #1,519,202, December 16, 1924 in the naine of Joseph Herman,and reference is had thereto. The loop circuit includes the batteries 11and 12, the sounder S, the key K and the armature and contacts of thereceiving relay 10. In the loop circuit 7 and the biasing circuit 8 arealso shown the windings of a balanced meter 9. Associated with themarking contact and the armature of the receiving relay 10 in the loopcircuit is the spark killer device, comprising the resistances 13 and 14and the condenserV 15 `for purposes which will be pointed outhereinfter. .There is also provided a break relay 6. 18. The winding 17consists of a small numberfof turns connected in series with the markingbattery 3. The winding 18 consists of a large number of turns connectedin a leak circuit19 from the armature of the pole This relay has twowindings, 17 and changer relay 1 to ground. The armature ci n relay 16is connected to the line L, and the contacts 20 and 21, which are termedthe sending and receiving contacts respectively, are connected to thepole changer armature andthe winding of receiving relay 10. Anadditional leak circuit 24 with a suitable resistance connects thearmature of relay 16 to the armature of relay 1. In series with relay10, there is also shown a meter 25. There is also provided a variableshunt resistance 22 around the `winding 17. I

Current flowing through the winding 17 tends to hold the armature of thebreak relay against the sending contact 20. through the winding 18 inthe leak circuit 19 opposes the eii'ect oi winding 17 when the armatureof the pole changer' 1 is on the marking contact, but aids it whenthearmature is on the spacing contact. By properly proportioning the shunt22 across the winding 17 and the resistance in the leak circuit 19, thenormal line current flowingy through the series winding 17 can be madeto ovepower the effect of the leak winding 18.

Current g;

Clt

Under this condition, the armature of the break relay 16 will alwaysstay on the sending contact 20, even though the armature of the polechanger 1 travels back and forth between its two contacts.

The receiving relay 10 has one winding, one end of which is connected tothe receiving contact 21 of the break relay 16, and the other end toground. A leak circuit 23 from the spacing battery 2 to the receivingcontact- 21 of the break relay serves to hold the armature of thereceiving relay 10 to its marking contact, thereby closing the loopcircuit when the local subscriber at A is sending. circuit 24 from themarking battery 3 through the armature of the pole changerl 1 to theline L neutralizes the edect of the'holding leak circuit 23 when thearmature of the break relay is on the receiving contact 21. Accordingly,the only current` flowing through the receivi-ng relay 10 under thiscondition is that from the distant end of the line. If desired, one ofthe leakcircuits 23 or 24: may be made variable, thereby permitting thereceiving relay 10 to be bia-sed to counteract ground potentialsandbi'ased signals. rlhe meter 25 in series with the receiving relaywill be found helpful in such cases.

The'apparatus at sta-tion B is substantially the saine as that atstation A with the exception that oppositely poled batteries from thoseutilized at station A are provided for sending marking and spacingimpulses. In other words, if the battery 3 at station A, utilized formarking impulses, is negative, then the battery 3', utilized a-t stationB for marking impulses, will be positive, and,l similarly, if spacingbattery 2 at station A is positive, then spacing battery 2 at station Bwill be negative. The reasons therefor will appear more fully from thefollowing detailed description of the operation of the device.

Y If the local subscriber at A issending, the line L will be grounded atthe di-stant station B through the receiving relay. The local receivingrelay 10 will then be held on its marking contact under the influence ofthe holding leak circuit 23, and the pole changer 1 will be operatedunder the influence of the subscribers key K. When the armature of thepole changer 1 rests on itsspacing contact, vthe armature of the breakrelay 16 will be held against the sending contactl 2O under theinfluence of the current through the winding 18 in the leak circuit 19.When the armature of the pole changer 1 rests on the marking contact,the leak winding-18 will tend to operate the break relay armature tothereceiving contact 21, but will be prevented from so doing by the linecurrent flowing through the winding 17 te the marking battery 3 andoverpowering the effect of the leak winding 18. The local subscriber atA, therefore, can continue to send.

Zhen the localsubscriber at A is-receiving,

The leak the armature of the break relay 16 will have been tripped toits receiving contact 21 in a manner to be pointed outhercinafter. Whenthe armature of relay 16 is on the receiving Contact 21, the linecurrent is completely disconnected from the windings 17 and 18. rFliesetwo windings will then be in series with the marking battery 8. Underthese conditions, the eiiect of the winding 18 will be sutlicient tooverpower the effect of the winding 17 and will serve to hold thearmature against the receiving Contact 21. rihe armature of thetransmitting relay 1 will be held on its marking Contact under theinfluence of its loop and holding windings 5 and 6 respectively. Theholding current in the receiving relay 10'from the circuit 28 will beneutralized by an equal and opposite current over the circuit 24 andarmature and marking contact of relay 1 to the marking battery 3.Accordingly, the re.- ceiving relay 10 will only be affected by the linecurrent from the distant station B which will flow through said relay toground, operating said relay.

If the subscriber at A is sending, and the distant subscriber at Bwishes to break the sending subscriber, he opens his key K. The openingof key K causes the armature of the pole changer relay 1 to move to thespacing contact, and accordingly negative spacing battery 2 will beconnected to the line. If the local subscriber at A is at that timesending a spacing signal his pole changer armature will be on positivebattery 2, and nothing will happen except that the line current will bedoubled. lVhen the local subscriber at A now closes his key to send amarking impulse, his pole chan ger armature will move to the markingcontact and connect the negative marking battery 8 to the iine. Withnegative battery thus connected to both ends of the line, the linecurrent will be reduced practically to zero, and practically no currentwill flow through the winding` 17. The negative current, however, willflow through the leak circuit 19 and the winding 18, and willlaccordingly trip the armature yof the break relay 16 from the sendingcontact 2O to the receiving contact 21. As soon as this occurs, thedistant spacing battery will operate the local rcceiving relay 10 to thespacing contact, thereby opening the loop circuitand energizing theholding windineV of the pole changerc The leak winding 18 of the breakrelay 16 will continue to hold the armature of the break relay againstthe receiving contact 21 as long as the subscriber at A keeps his keyclosed to receive signals from the distant station B. This it can do,because, as has been previousl 1 pointed ont, the line current iscompletely disconnected from the pole changer armature and from thewinding 17, and the windings 17 and 18 are connected in series with thebattery 3. Under these conditions, the winding 1.8

vwill overpower the winding 17 and render the latter windingineffective.

To illustrate how battery was put on the line by the distant subscriberat B, assume that the local subscriber at A, after receiving a fewsignals, now intends to break the distant subscriber. l-le openshis keyK, which deenergizes both the loop and holding windings of the polechanger 1, thereby operating the armature of the pole changer 1 to thespacing contact S. rlhe current from the spacing battery flowing throughthe leak Winding 18 of the break relay Will operate the armature of thatrelay to the sending contact 20, thereby disconnecting the line from thereceiving relay and connecting it to the armature of the pole changer 1.The local spacing battery 2 will therefore be connected to the line, andwill trip the distant break relay 16 in the same manner as alreadydescribed with respect to relay 16.

Because of the fact that both the holding winding 6 and the loop winding5 are deenergized by the opening of the subscribers key K, the sendingsubscriber might not receive a clear break signal. This break relay willbe operated to the sendingcontact when he opens his key, and to thereceiving contact when he closes his key, as long asthe breakingsubscriber maintains spacing battery on the line. This might produceshort clicks in the sending subscribers loop circuit, which would bevery confusing and prevent satisfactory operation of thesystem. 'loavoid this, a lag is introduced in the operation of the holding winding6 of the pole changer, so that this winding fails to release, in theinterval between markings and spacings, of ordinary sending. This isaccomplished by connecting the spark killer device, consisting of theresistances 13 and 14 and the fairly large condenser 15, across theholding winding circuit. The operation of the holding winding is then asfollows:

Assume that the local break relay 16 has just been tripped by thedistant spacing battery as the local subscriber at A closes his key tosend a marking impulse. The receiving relay will open up, connecting theholding winding in series with the loop. The spark killer will then becharged to a high potential, due to the effect of the loop batteries 11and 12. The holding circuit, it is pointed out, has such a largeresistance compared to the loop that practically the full voltage of thebatteries is impressed across it. lf one ofthe loop batteries is thendisconnected by the opening of the subscribers key, the spark killerwill discharge through the holding winding and keep it energized duringthe period in which the subscriber keeps his key open. The pole changerwill therefore fail to release, and a clean break will result.

From the above description it will be seen that in a system employingtermina-l stations of this type the breaking features at each station iscontrolled by the application to the line at the dist-ant station of anopposing battery to that at the first station and the attendant reducingof the line current practrically to nothing. This may be done as dierentbatteries are used for marking and spacing at one station than are usedfor marking and spacing at the other station, as has been pointed outheretofore.

ln the drawing the telegraph repeater of the invention is shown asinterconnecting sections of the line L terminating at the stations A andB. The repeater itself comprises a receiving relay havingl a winding 30,a break relay having windings 4l., 42, and 43, and a transfer relayhaving a winding 50. The break relay controls the transfer relay. Thetransfer relay controls the armatures 51, 52, 53, and 54. The receivingrelay controls the armature 31. ln the drawing the B station is shownusing negative battery for spacing and the A station utilizing positivebattery. Viith the transfer and break relay con,- tacts as shown theline to station A is connected to the receiving relay winding and theline to station B is connected to the receiving relay arn'iature 31 andto ground through the break relay winding 42. Negative and positivebatteries are provided which may be connected to the armatures 53 and 54respectively through either the break relay windings 41 and 43 or thebalancing in-V ductances 90 and 91. Signals coming from station Aoperate the receiving relay which in turn repeats signals into the lineto station B. lllhen the operator at A sends a mark negative battery isconnected to the line to B and when a space is sent from A the operationof the receiving relay will cause positive battery to be connected tothe line to B. The winding41 of the break relay is connected in serieswith a negative transmitting battery and serves to hold the break relayagainst the proper contact during the transmission of a marking signal.

To transmit a break signal the operator at B opens his key, therebyconnecting negative battery to the line. As soon as the subscriber' at Asends a mark, the line to station B is connected to negative battery atthe repeater station, thereby reducing the line current practically tozero. The effect of the winding 41 is thereby destroyed and the breakrelay will operate to the otherV contact under the influence of thewinding 42. The operation of the break Arelay causes a transfer relay tooperate and connect the line to station B to the receiving relay windingand the line to station A to the receiving relay armature 31. At thesame time the winding 41 will be disconnected from the negative batterytap and a similar winding 43 is connected into the positive battery tap.This `is necessary because the positive battery will be marking batterywhen transmitting to the subscriber at A. After the transfer relay hasoperated, the receiving relay will still be on the negative contact,because thev negative spacing battery from the line to station B willtake the place of the negative marking battery from line to station A.Consequently, the receiving relay armature 3l will remain on negativebattery and this battery will be connected to the line to station A andwill trip the break relay thercat in the manner previously pointed ont.TvVhen the subscriber at B begins to send, the winding 4:3 of the breakrelay will hold the break relay to the proper Contact nntil a breaksignal is received fr ni the subscriber at A.

IVhile the invention has been disclosed in certain specific arrangementswhich are deemed desirable, it is understood that it is capable ofembodiment in many other and widely varied forms without departing fromthe spirit of the invention as defined in the appended claims.

What is claimed is:

1. In a telegraph system, a repeater station for interconnecting twoline sections comprising a single receiving relay, switching meanswhereby said relay may be connected to either of said line sec-tions,sources of current of different polarity, means controlled by saidreceiving relay for connecting said sources to said switching means, abreak relay, and a transfer relay control-led by said break relay, saidVtransfer relay controlling said switching means.

2. In a telegraph system, a repeater station for interconnecting` twoline sections coinprising a single receiving relay, switchi-ng meansassociated with each of said line seetions whereby said receiving' relaymay be connected to either ofsaid line sections and the armature of saidreceiving relay may be connected to the other of said line sections,sources of current of different polarity associated with said armature,a break relay, and a transfer relay controlled thereby, said transferrelay being adapted to reverse said switching means.

8. In a telegraph system, a repeater station for interconnecting twoline sections comprising a. receiving relay, switching arrangementsassociated with each of said line sections whereby said receiving relaymay be connected to either of said line sections and the armature ofsaid receiving relay-may be connected to the other of said linesections, sources of current of different polarity associated with saidarmature, a break relay, the operation of said break relay beingdependent upon a reduction below normal in the line current in the linesection with which said receiving relay armature is connected, andtransfer relay controlled by said break relay., said transfer relaybeing adapted to reverse said switching arrangements,

January, 1928.

JOSEPH HERMAN.

